Generally, polymer-coated board is used in containers and packages intended for liquid foodstuffs and other liquid-based or wet products. Typical products, which the packages and containers made of polymer-coated board are intended for, comprise different liquid and wet foodstuffs, such as milk products, water, juices, wine, coffee and other hot drinks, soups, desserts and processed food.
The inner polymer layer of a package or container protects the board against moistening and wetting and, depending on the polymer grade, provides an oxygen and/or flavour protection for the product contained in the dosed package. The polymer can also protect the board against the grease or fat contained in the product. Furthermore, the polymer coating makes it possible to heat-seal the board, when making the packages or containers. In addition to the polymer-coated inner surfaces, the inner cutting edges or so-called raw edges of the cardboard package or container may be exposed to the wet or liquid product, the liquid being possibly absorbed into the board through the edges. To avoid this, the board may be folded around its edges, so that the raw edges are hidden inside the casing of the seamed package or container or that they are turned onto its outer surface, or the edge of the board may be skived and thereafter folded double, so that the raw edge is closed. Another approach to the problem of absorption of the raw edges has been to prevent the absorption by suitable sizes of the board.
Another way of making a board container or package impermeable to liquid and gas is to provide the board used for the packaging with a metal foil. However, the disadvantages of such packaging include high manufacturing costs, non-biodegradability of the foil layer and problems of regeneration of the packaging material.
It is becoming more and more important that packages are environmental friendly, i.e. that they are recyclable and/or biodegradable. A big advantage with a fiberbases package is that they are recyclable. However, the fiberbased containers or packages for packaging food or liquids used today are either foil or polymer laminated making it more difficult to recycle the used packages.
The use of biodegradable polymers in the coating of containers and cups is an alternative. However, the presence of polymers, biodegradable or not, still causes problems during recycling of the board since the pulpability of the board is detracted. Furthermore, the biodegradable polymers are very expensive and more difficult to extrude to a board.
Thus, there is a need for a more environmentally friendly container which is more economically beneficial to produce at the same time as it is suitable for packaging food and/or liquids.